This post is one of a series of posts sponsored by UPS in support of the Inc Growco Conference held April 6-8 in Las Vegas, NV

The category of for profit social enterprise is a rather unique one still. The idea of blending social mission with a business that happens to make money is hard for some people to wrap their heads around, but its a growing trend among entrepreneurs.

The category’s most notable example is probably Tom’s Shoes. Blake Mycoskie’s shoe company is a marketing and financial powerhouse that provides millions of pairs of shoes for children around the world.

This past week I was introduced to another such company that has a great story to tell and is quickly becoming a financial success as well.

They collect and sell books online to fund literacy initiatives worldwide. With more than 8 million new and used titles in stock, they are a self-sustaining, triple-bottom-line company that creates social, economic and environmental value for all stakeholders.

They were founded in 2002 by three friends from the University of Notre Dame who started selling textbooks online to earn some money, and ended up forming a pioneering social enterprise — a business with a mission to promote literacy.

In addition to selling new titles, Better World Books supports book drives and collects used books and textbooks through a network of over 1,800 college campuses and partnerships with over 2,000 libraries nationwide. So far, the company has converted more than 53 million books into over $8.6 million in funding for literacy and education. In the process, also diverted more than 26,000 tons of books from landfills.

Even as the company grows rapidly, creating a legitimate online alternative to Amazon.com, they continue to explore ways to stay true to their original mission. CEO David Murphy claims this might be the biggest challenge, but it’s also the most important thing they can do.